From various internet sources, the Peregrine Class escort fighter / courier is described as anywhere between 14 and 25 meters. Personally I prefer the larger 82 foot (25 meters) version, making the central fuselage (less impulse engines and wings) at 55 feet long and 39 feet wide.
This is more constant with what I imagine as a warp capable "heavy fighter." The larger version's warp drive would be of a similar size to the nacelles on a runabout. Giving it the same maneuverability, speed and range. However it would be equipped with a larger warp core to power it's phasers and shields. It would also have a habitat area about that of the forward section of a runabout, spartan but better than living in a cockpit. Enough for a crew of four.
http://akiraclass.wetpaint.com/page/Peregrine+Class+Raider
This is more constant with what I imagine as a warp capable "heavy fighter." The larger version's warp drive would be of a similar size to the nacelles on a runabout. Giving it the same maneuverability, speed and range. However it would be equipped with a larger warp core to power it's phasers and shields. It would also have a habitat area about that of the forward section of a runabout, spartan but better than living in a cockpit. Enough for a crew of four.

http://akiraclass.wetpaint.com/page/Peregrine+Class+Raider